Crucially, all of this evidence gathering can begin immediately, both in areas where Russian forces have withdrawn, and in parts of Ukraine that are still contested but where communication has not been severed. The European Union, the UN, multiple human-rights groups, the secretary-general of NATO, and Ukraine’s prosecutor-general recently have either called for investigations of possible war crimes in Ukraine, including rape, or have offered their help in carrying out the investigations.

It may seem fanciful at this stage—with Russia still hammering Ukrainian territory, and no resolution to this war in sight—to plan for a period in which Russian soldiers might face trial for their abuses. Yet it is not at all out of the realm of possibility: Neither Russia nor Ukraine are subject to International Criminal Court prosecutions, but Ukraine has previously accepted the court’s jurisdiction. Another possibility is that countries that have begun prosecuting war crimes unrelated to their citizens, such as Germany, may begin proceedings on the basis of the concept of universal jurisdiction. This road is a long one, and there is no guarantee of success, but high-quality evidence-gathering in Ukraine now improves the odds considerably.